John Gruber outlines the changes to Spaces in 10.5.3. I’ve put them to test, because although I used Spaces I did get annoyed by the swapping by changing to an app.
John did miss something though. If you have an application bound to a space, it’s preference is still respected. If I have Safari open and bound to Space 1, I switch to Space 2 and select Safari I remain in Space 2 until I open a new window. Then I’m transported back to Space 1 with a new Safari window. It’s logical behaviour but I just wanted to point it out incase people got confused.